How the interviewer opens it
“Design a platform where patients find providers and book appointments across clinics. The platform must prevent provider conflicts and reflect clinic schedule changes.”
The prompt is vague on purpose. The first minutes are for you. Reduce the prompt to the core features and agree on the numbers before you draw.
What to clarify first
- Coverage
- Request volume
- Latency
- Consistency and durability
- Calendar ownership and clinic contract
- Clinic changes
- Appointment times
- Patient flow
- Retention and access
- Scope limits
The interviewer has the answers. In a SysRound round, Alex gives these answers, as a real interviewer does.
Scope of a strong answer
Core requirements
- Find providers by location, specialty, and date
- View available appointment times
- Book or cancel an appointment without provider conflicts
- Reflect clinic schedule changes in displayed availability
Usually out of scope
- Medical records and clinical advice
- Insurance claims and payments
- Room and equipment schedules
- Conflicts between a patient's appointments
- Implementation of clinic calendar systems
What interviewers ask about
- Provider time conflicts
- Patients and clinic staff can reserve overlapping intervals through different channels. A local check cannot protect a calendar that other systems also change.
- Changes to availability
- Clinic changes can arrive late, twice, or out of order. The platform must repair its calendar view without treating stale availability as a reservation.
- Repeated requests and uncertain outcomes
- A clinic can accept an appointment before the platform receives the result. A cancellation can arrive while the original result remains unknown.
Common mistakes
- The design treats the local availability view as the authority for reservations.
- The design uses a local lock that clinic staff can bypass.
- The design checks equal start times but misses partial overlaps.
- The design treats a timeout as proof that the clinic rejected the appointment.
- The design assumes retries are safe without a clinic deduplication contract and a retention limit.
- The design assumes asynchronous database replication preserves every acknowledged request after a zone failure.
The bar by level
- Senior (L5/E5)
- Defines calendar authority across all appointment sources. Handles uncertain results, durable cross-zone acknowledgment, cancellation races, and event repair. Explains time-zone behavior.
- Staff (L6+/E6+)
- Tests whether clinic contracts support the guarantees. Defines retention limits, degraded behavior, and regional failure boundaries. Plans source migration, auditable recovery, and privacy controls.
Sources · 1 reference
These records explain where the question appears. A company tag or candidate report does not guarantee a future interview question.
SysRound · 1 record
No company association
Design a doctor appointment booking system
Reported date not specified
Source snapshot: Nov 12, 2026
View source